How to influence strawberry health
The nutrient status of strawberries plays a major role in plant health and fruit quality. Too much nitrogen results in excessive plant vigour, leading to delayed ripening and malformed fruit, and greater incidence of disease. However, the use of a balanced fertiliser programme helps to reduce disease in the fruit through strengthening the skin.
Nitrogen excess increases disease susceptablity
Excess nitrogen during fruit growth and development increases disease susceptibility and the softening of fruit. Often leading to a shorter shelf life and fruit that is quicker to rot.
Calcium deficiency causes tip burn
One of the most common deficiency symptoms in strawberries is tip burn, where youngest leaves (at the heart of the plant) and the growing points have necrotic margins, and often deformed or folded in appearance.
Strawberries grown in greenhouses and polythene tunnels are very susceptible to this typical leaf and flower tip burn, especially when the Ca level in the nutrient solution drops below 2mmol (80mg Ca/l). Injury begins on emerging young leaves as necrosis near the tip. As they expand, the leaf blades have light green borders. The next leaves are crinkled, the tips fail to expand fully and turn black.
Calcium supports root development and crop establishment, including the growth of young leaves and buds. It plays a key role in maintaining the physiological stability of plant tissue ensuring good plant structure and health. For example, calcium builds strong cell walls and is vital to cell membrane integrity and permeability. In addition, Ca helps improve the plant’s tolerance to disease and salinity, maintaining good, stress-free growth.
Poor calcium uptake – particularly when it is out of balance with K and Mg supply – leads to necrosis and tip burn. In this trial, petiole necrosis, flower stem lesions and tip burn of runners increased with decreasing Ca and increasing Mg availability in the nutrient solution. Tip burn can be minimized by lowering the EC at night. Calcium uptake and distribution is favored at night when the xylem sap pressure can push water and calcium into the low or non transpiring tissues such as enclosed leaf tips and fruit. Regular calcium supply throughout the production cycle ensures that Ca required for fruit integrity, will find its way into the fruit also boosting yields.
Calcium helps to reduce disease severity
Calcium can help to reduce levels of mould on fruit post harvest when applied pre harvest as a foliar application.
Boron improves calcium distribution
Boron applied with calcium often improves yield and quality. It has been shown in other crops e.g. tomatoes, that adding boron to calcium applications will improve calcium distribution in new tissues in the plant.
Silicon improves mildew resistance
Silicon also has an effect on fruit quality and there are indications that it can improve disease tolerance due to its role in reinforcing the cell wall.
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How to increase strawberry fruit numbers
Balanced nutrition is needed to ensure high fruit numbers however potassium, boron and zinc are particularly important to ensure good flower initiation and fruit set.
How to influence strawberry quality
Balanced crop nutrition is needed to achieve good quality strawberries but potassium, calcium and boron have particularly important roles in maintaining quality.
How to improve strawberry fruit quality
Potassium is particularly important in terms of berry quality improving berry appearance and ensuring a good taste to the fruit.
How to extend strawberry shelf life
Strawberries are highly susceptible to bruising and post-harvest decay. Calcium helps improve fruit firmness, prolongs keeping quality and extends shelf life.
